drm sis: initialize object_idr

The filed object_idr of struct drm_sis_private was introduced with
commit http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=6de8a748881f1cd9d795454da2b6db616d5ca3d7

 .

The idr_init(&dev->object_name_idr) is called instead of
idr_init(&dev_priv->object_idr) by mistake, leaving object_idr
uninitialized. Correct this.

This patch was not tested because of lack of hardware.

Signed-off-by: Márton Németh <nm127@freemail.hu>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>